Inventing a spaceship takes a smart brain. But to put one in orbit takes a brain with extraordinary social skills. That's because getting from concept to launch pad takes more than technology, it requires people to cooperate on a massive scale.

In our series The Human Edge, NPR has been looking at how evolution has made our species so successful.

Today, NPR correspondent Jon Hamilton explores why our social nature has given us such a big advantage.

JON HAMILTON: Before kindergarten, social skills aren't such a big deal. But that changes pretty quickly.

Lisa Daxer was in elementary school when she noticed that she wasn't like her classmates.

Ms. LISA DAXER (Biomedical Engineering Major, Wright State University): I realized that I was different in more ways than just being better at reading and math. I realized that they had friends and I didn't.

HAMILTON: She never did learn to navigate the social landscape of grade school.

Ms. DAXER: About in the 5th grade, I realized that I should probably to stop making friends because it wasn't going to be very successful.

HAMILTON: And social stuff is still hard for Lisa. She's 27 now and going to college in Dayton, Ohio.

Ms. DAXER: I go to Wright State. I'm a biomedical engineering major and I have a weird brain. They call it autism. But, to be honest, the label matters less than the fact that I'm who I am. I'm here because I like to learn.

HAMILTON: Autism often makes Lisa feel like an outsider, an alien. But it's also given her an unusual perspective on the social behavior of people she calls neurotypical.

Ms. DAXER: Neurotypical is anyone who doesn't have a weird brain, anyone who is in the middle of the neurological bell curve.

HAMILTON: Lisa writes about neurotypicals in a blog called Reports from a Resident Alien. And we asked her to record some of her observations in an audio diary.

Ms. DAXER: Hi, this is Lisa. It's 12:25 P.M. I am sitting in the student union atrium. And I am watching people.

Professor SIMON BARON-COHEN (Developmental Psychopathology, University of Cambridge): Lisa is not the first person with autism to describe herself as almost like an alien, observing other humans.

HAMILTON: Simon Baron-Cohen studies autism at the University of Cambridge in the U.K. He says people like Lisa have taught scientists a lot about the way humans interact socially.

Prof. BARON-COHEN: So we didn't really focus on how complex social development is until people with autism pointed out to us that this is something that doesn't always just develop naturally.

HAMILTON: The importance of eye contact, how to read facial expressions and social cues, how to fit into a group - these are so much a part of the way humans relate to one another that most people aren't even aware of them. But Lisa is.

Ms. DAXER: Do you want to go in the...

HAMILTON: Standing on a grassy slope on campus, Lisa blends in with the other students; baggy clothes, backpack, a computer thumb drive dangling from a lanyard around her neck.

(Soundbite of conversations)

HAMILTON: But inside the Student Union, it's a different story.

Ms. DAXER: Coffee shop, the lifeblood of the college; lots of people, basically. They eat here. They hang out here. They study here. I don't.

HAMILTON: Lisa watches them through oval glasses but she doesn't meet their eyes or talk to anyone. She says her fellow students tend to clump.

Ms. DAXER: By default, they socialize. You have to actually interfere to stop neurotypicals from socializing. They're drawn to each other like nonexistent unipolar magnets.

(Soundbite of laughter)

HAMILTON: In coffee shops, at parties, even while dissecting human hearts in the anatomy lab.

Baron-Cohen says this constant socializing is no accident.

Prof. BARON-COHEN: Amongst primates, particularly social primates, it is important to stay within the group. And if we took an evolutionary perspective, that would be for physical survival. A member who becomes separated from the group is at increased risk of predators, to put it bluntly.

HAMILTON: So the humans who survived were predisposed to have what you might call a social brain. It's still with us - think fraternities or Facebook. If you want to be part of a group, you constantly monitor your status with other members.

Prof. BARON-COHEN: You're picking up cues about what they might find acceptable or interesting or unacceptable. And picking up those cues very early could mean the difference between inclusion and exclusion. If you've done something that might offend somebody or upset somebody, it's good to notice that quickly, so that you can fix it.

HAMILTON: Before they defriend you.

Belonging to a group also means following unwritten rules, like not violating taboos. And our social brains are really good at this - it doesn't take long for most kids that someone is fat or old or stupid.

To Lisa's brain, though, these are just facts. She had to make a list of topics that seemed to offend neurotypicals.

Ms. DAXER: Don't talk about sex. Don't talk about the anatomy lab. Don't talk about surgery. Don't talk about anything that happens in the bathroom.

(Soundbite of laughter)

HAMILTON: And that list is far from done. She recently figured out that death is off-limits, too.

Ms. DAXER: I hadn't realized that and had been talking about it to my friends until someone, actually the church librarian, mentioned to me that she thought it was a depressing topic to talk about.

HAMILTON: Lisa still doesn't really get taboos. She thinks these subjects just irritate neurotypicals, the way people with autism can be irritated by certain sounds or certain textures.

Ms. DAXER: We all avoid different things. I avoid polyester clothing. They avoid talking about death.

HAMILTON: But there's more to it than that. Taboos are just one of the vast number of social rules we don't even know we know. Don't stand too close; don't stare; take turns. But this is just the beginning of what our social brains learn to do.

Lisa says she realized this when she lived in a group house with other students.

Ms. DAXER: It's kind of funny. One of my other housemates loved the show "Friends." And I think it's a silly show.

(Soundbite of theme song, "Friends")

Ms. DAXER: A very neurotypical show actually, it's all about relationships.

HAMILTON: Unconsciously mimicking their smiles, their frowns, their body language. To Lisa, that was a revelation. It's something she doesn't do.

But Baron-Cohen says it's something most children start doing before age two.

Prof. BARON-COHEN: They're looking up at people's faces. They're paying attention to people's facial expressions and they're responding. So if someone looks sad, they will mirror the expression.

HAMILTON: This sort of mirroring is probably the basis for one of the most complex and important social skills: Empathy.

The typical human brain has evolved an extraordinary ability to see the world from another person's point of view. That helped our ancestors get along. It's also the reason humans, and some other species, care for a member of their group who is injured or sick.

Lisa learned a lot about empathy from one of her housemates.

Ms. DAXER: I would call her super-neurotypical, because she had extremely good social skills.

HAMILTON: At the time, Lisa was feeling increasingly depressed and isolated. She says this woman seemed to understand.

Ms. DAXER: I think she knew that I was hurting and she didn't want me to hurt anymore.

HAMILTON: But Lisa's depression got worse. Eventually, she ended up in the hospital.

Ms. DAXER: She visited me in the mental ward. In our society, being crazy is considered very, very frightening. And this girl, when I had depression, she visited me in the mental ward. That takes courage; that takes friendship; that takes empathy.

HAMILTON: Simon Baron-Cohen say empathy may have evolved from the relationship between parent and child.

Prof. BARON-COHEN: If the parent has empathy, they're going to be able to imagine that the infant might be in pain or discomfort or hungry or tired or in need of affection; a whole range of mental states. So empathy would have promoted better parenting.

HAMILTON: And the genes involved in empathy would get passed on to the next generation.

But empathy isn't just about raising children and caring for the sick. If you can look at the world from another person's point of view, it's much easier to take on common goals. You can cooperate, which is one of the keys to human success.

(Soundbite of birds)

Ms. DAXER: Hey, this is Lisa. I'm sitting outside my church in the parking lot. So at church, something interesting happened. Pastor comes up and says, okay, we need to change the fellowship hall to a dining hall. So they had that fellowship hall turned from a place with, you know, a couple of hundred chairs to a place with a couple of dozen tables and chairs and tablecloths and place settings and everything in about 15 minutes flat.

HAMILTON: Dozens of people working together with hardly a word exchanged - just glances, and body language, and a common purpose.

Prof. BARON-COHEN: Again, it's something that you see in humans. You don't see very much of that in other species. You know, the idea that two humans could pick up a log that's way too heavy for one person to carry but between the two of them, they can lift it and move it. And, you know, that's obviously enabled humans beings to do all kinds of things, like put up buildings.

HAMILTON: Or spaceships. Lisa sometimes asks herself why, from an evolutionary perspective, people with autism are still around. She's come with one possible scenario. It involves a caveman named Bob.

Ms. DAXER: So let's say Caveman Bob invents fire. But because he's autistic, he's too nerdy for the cavewomen. So he doesn't have any children. I mean, how is that an advantage when it comes to natural selection? You'd think it wouldn't be.

HAMILTON: But if Bob's discovery gives his tribe an advantage, his relatives will be able to have more children even if he never has any. So his genes, including those involved in autism, will be passed on to future generations. Baron-Cohen says that's a plausible explanation.

Mr. BARON-COHEN: As tool users, you know, we always needed individuals in the group who could invent new tools, whether we're talking about in Stone Age, just flints, or in the modern age, new computer chips.

HAMILTON: Of course, that still doesn't account for autism that is completely disabling.

Lisa Daxer says she doesn't want a typical brain. Her autism is part of who she is. And she enjoys that her brain loves patterns and facts. But she says she will probably always feel like a bit of an alien.

Ms. DAXER: I wonder what it is like to be one of a unit of two. I don't know. But then again, they'll never know some of the beautiful things I see, the tiny little patterns on a leaf or the intricacies of a circuit or learning a new fact and almost squealing in joy because it's so beautiful.

HAMILTON: The gap between Lisa and the neurotypical world will never disappear. People still treat her as different. But she has done a remarkable job of adapting. She has learned to make friends and to find colleagues who value her scientific work. And Lisa says she has come to appreciate the power of what neurotypicals can do with their social brains.

Ms. DAXER: I've seen them help people who are hurt. I've seen them draw together networks of people to make the world better. I've seen them connect different sorts of minds so that we could all communicate and live in a single society. I know you take it for granted, but it's really very amazing to be able to do that.

HAMILTON: Jon Hamilton, NPR News.

(Soundbite of music)

SIEGEL: At our website, you can find all the stories in our series on evolution, including how language evolved and how a meat-based diet made us smarter. Those and other stories about the human edge are at npr.org/science.

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